Antibacterial Activity of Essential Oils Extracts from Cinnamon, Thyme, Clove and Geranium Against a Gram Negative and Gram Positive Pathogenic Bacteria

Abstract

Essential oils and other extracts of plants have evoked have been screened for their potential uses as alternative remedies for the treatment of many infectious diseases. In this context, the aim of this study was to investigate the antibacterial activity of the essential oils from Cinnamon, Thyme, Clove and Geranium against four strains of Gram negative bacteria and two Gram positive bacteria. The in-vitro antimicrobial effects of these essential oils was determined by the disc diffusion method. The Minimum Inhibitory Concentration (MIC) was evaluated by using the broth serial dilution method and Minimum Bactericidal Concentration values (MBC) were defined as the lowest concentration of sample which resulted in ≥99.9% kill of the initial inoculum. The antibacterial effect was deemed bactericidal or bacteriostatic depending on the ratio: MB/CMI. Cinnamon possesses an important antimicrobial activity against all tested microbes, with the inhibition zones ranging from 26 to 32 mm. The essential oils of thyme and Clove showed the antibacterial activity with inhibition zones at 16–22 mm and 16–20 mm, respectively. However, the Geranium essential oil failed to inhibit any of the tested strains. Both gram-positive and gram-negative bacteria were resistant to this essential oil. Results according to the MICs and MBCs revealed that the essential oil from Cinnamon showed the most remarkable bactericidal effect. The essential oil from Cinnamon might be exploited as natural antibiotic for the treatment of several infectious diseases caused by the pathogens germs and conservation agents in the food.